Heating device, camera system, external rear view device, motor vehicle and heating method

ABSTRACT

A heating device for a lens barrel of an automotive camera assembly includes a heating element adapted to apply heat along the circumference of the lens barrel, and a tension socket and/or a tension ring adapted to press a ring-shaped part of the heating element against the lens barrel circumference. A camera system, an external rear view device, and a motor vehicle, each with at least one such heating device are also described.

CROSS-REFERENCE TO RELATED APPLICATIONS

This application is a continuation-in-part of U.S. Pat. Application No. 17/216,059, filed Mar. 29, 2021, which claims the benefit of foreign priority to German Patent Application No. DE 10 2020 108 948.1, filed Mar. 31, 2020, each of which is hereby incorporated by reference in its entirety for all purposes.

BACKGROUND 1. Field of the Invention

The present disclosure relates to a heating device, a camera system, an external rear view device, a motor vehicle and a heating method.

2. Related Art

A motor vehicle can be equipped with a camera monitor system (CMS) comprising two cameras per side or wing, i.e. a wide angle camera and a farsighted camera. A heating device for the farsighted camera is described e.g. in PCT/EP2019/077092.

In particular the present disclosure relates to a heating device adapted for use with the wide angle camera and suited for heating a lens barrel of an automotive camera assembly. For that purpose, the heating device comprises a heating element adapted to apply heat along the circumference of the lens barrel.

The heat conduction from a conventional heating element to a lens barrel is subject to large losses due to heat conduction in the opposite direction. Also usage of a simple heating foil is often subject to damages, in particular due to peeling off and the like.

US 2019/0113743 A1 discloses a camera for a vehicular vision system which includes a housing and a lens barrel including a lens. The camera is configured to be disposed at an exterior portion of a vehicle so as to have a field of view exterior of the vehicle. The heating device is disposed at an exterior of the lens barrel. The heating device includes a thin foil heating element that at least partially circumscribes the lens barrel. The heating device includes an electrical lead that is configured to electrically connect to an electrical connector of the vehicle when the camera is disposed at the exterior portion of the vehicle.

Further, the disclosure relates to a method for controlling a heating device in particular for a lens barrel of a camera of an automotive camera assembly, but also for a cover glass of a camera of an automotive camera assembly.

In case of icing or demisting, a melting enthalpy and a vaporization enthalpy (melting heat) must be introduced to reach temperatures above 0° C. and to vaporize drops on a surface. In order to overcome this “thermal hurdle”, a considerably higher power must be introduced at the start of heating. But in case the heating power that is applied at the beginning is applied over a too long period of time, too high temperatures will occur, which may cause damage.

US 2019/0113743 A1 describes a temperature sensor for sensing a temperature at said camera, wherein, responsive to an output of said temperature sensor that is indicative of the temperature at said camera being below a threshold level, a control operates said heating device to increase the temperature of said lens barrel of said camera. In addition, responsive to a determination of current drawn by said heating device, a control estimates a temperature at said camera, and said control controls operation of said heating device based at least in part on the estimated temperature. Still further, said heating device is responsive to determination that a power consumption of said heating device reaches a threshold level.

SUMMARY

The present disclosure provides a heating device for a lens barrel of an automotive camera assembly, comprising a heating element adapted to apply heat along the circumference of the lens barrel, characterized by a tension socket and/or a tension ring adapted to press a ring-shaped part of the heating element against the lens barrel circumference.

According to one embodiment the heating device further comprises a heat transfer ring, preferably comprising aluminum, and/or a heat transfer paste between the ring-shaped part of the heating element and the lens barrel, and/or a heat transfer paste between the first ring-shaped part of the heating element and the socket and/or the torsion ring.

It is proposed that the socket comprises a recess through which a second part of the heating element can pass from the ring-shaped, first part of the heating element to a connector, with preferably the recess being selectable from a plurality of recesses, the second part being bar shaped, and/or the connector being adapted to be connected an electronic control unit.

Embodiments of the invention are further characterized in that the socket comprises connecting means for attaching the socket to a camera housing, in particular via a push and/or snap connection, with preferably the connecting means comprising at least one opening adapted to receive at least one projection or rib of the housing and/or being adapted to interlock with the camera housing.

It is also proposed that the socket comprises a rim embracing at least the first ring-shaped part and the lens barrel, and/or an inner ring extending from the inner surface of the socket and/or a shoulder, in particular provided by a S shaped cross-section at the end of the socket facing away from the housing, to snap fit around at least the first ring-shaped part and the lens barrel, preferably with the heat transfer ring, the heat transfer paste and/or the tension ring interposed between the first ring-shaped part and the lens barrel.

Still further embodiments can be characterized in that the socket comprises an elastomer material, preferably is made of rubber, in particular formed as a rubber cap, and/or has an inner diameter smaller than the outer diameter of the lens barrel carrying at least the first ring-shaped part of the heating element, and/or covers the lens barrel in a form-fit manner with a given preload.

In addition, it is proposed that the tension ring is provided with a slit, preferably between two end pieces having a complementary geometry and/or forming together a projection or rib, and/or made of metal.

It can also be proposed that the socket is mounted on the tension ring, with preferably the two end pieces engaging a further recess of the socket.

Embodiments of the invention can be characterized in that the heating element is L-shaped in side view, with a first leg being provided by the first part and the second leg being provided by the second part, and/or the second part of the heating element is adapted for connection with a plug and/or the electronic control unit, in particular via at least the connector and/or a cable, and/or the heating element comprises a heating foil, at least in its first, ring-shaped part.

A heating device of the present disclosure can further comprise at least one temperature sensor connected to a controller and/or the electronic control unit, in particular via a cable and/or a plug, for controlling the heating of the heating element.

It is proposed that the temperature sensor is arranged within the tension socket and/or the tension ring.

It is also proposed that the level of power applied to the heating element and/or the time of applying power to the heating element and/or the heating curve is controlled depending on the ambient temperature and/or the temperature measured by the temperature sensor, wherein preferably, a higher power level is applied in a first period of time, preferably between 60 to 200 seconds, than in a second period of time, and wherein preferably in case said temperature is at least -5, 0 or +3 degree C, there is only one power level applied.

In summary, the present disclosure overcomes drawbacks like a loss of heating device energy by radiation wind chill and mechanical contact to cover and housing elements as well as a detachment of a heating element caused by peeling off in some places, with the respective lost contact leading to heat dissipation problems hot spots within the heating element and even a destruction of the heating element. That is, all these drawbacks can be overcome by making usage of a tension socket e.g. in form of a rubber cap and/or a tension ring e.g. in form of a metal ring that surround(s) the heating element, in particular in form of a heater foil, which is mounted on lens barrel circumference.

The rubber cap can cover the lens barrel in a form-fit manner with a given preload such that a uniform service pressure to the normal of the lens barrel exists. Preferably the cap has at least one recess through which the heating element can be fed to a connector and two recesses on the side which are fitted into grooves or ribs on a camera housing.

The metal tension ring that surrounds the heating element on the lens barrel applies a uniform tension to it. An additional advantage is that more power can be applied to the heating element because the tension ring also conducts heat aa it is formed from a metal, in particular aluminum.

According to another aspect of the disclosure, a camera system for a motor vehicle with the heating device of the disclosure is provided.

Still further, an external rear view device with such a camera system is provided wherein the heating element is adapted to be connected to the electronic control unit of the rear view device and/or the vehicle equipped with the rear view device, in particular via a bus system, like the CAN bus system.

In addition, according to a further aspect a motor vehicle with at least one heating device of the present disclosure, at least one camera system according to the present disclosure and/or at least one external rear view device according to the present disclosure is provided.

Such a motor vehicle can be characterized in that the heating element is controlled depending from at least one characteristic parameter of the vehicle, in particular the heating element being activated only during a driving state of the vehicle.

According to a further aspect, the present disclosure provides a method for controlling a heating device for a cover glass or lens barrel of an automotive camera assembly, in particular according to the present disclosure, characterized in that there are 2 power levels for temperatures below at least one threshold temperature, preferably below + 3, 0 or -5° C., and otherwise there is only 1 power level, wherein, in case of 2 power levels, the first level is adapted to melt ice and the second level is adapted to avoid icing and/or evaporate water droplets, and in case of only 1 power level, the same is adapted to avoid icing and/or evaporate water droplets. In other words, when applying the various power levels, there are two power stages. When ambient temperatures are above the threshold temperature, the same power level may be applied at the first stage and the second stage, whereas when ambient temperatures are below the threshold temperature, different power levels may be applied at the first and second stages.

The method of the present disclosure can comprise a first step of determining whether the motor vehicle is in a driving state and applying power to the heating element only in case the motor vehicle is in a driving state. The driving state may include when the vehicle is turned on and capable of being set to a forward, rearward, or neutral driving mode, or another comparable mode. For instance, the vehicle may not be in a driving state when it is in a diagnostic state.

Such a method can further comprise a second step of determining the temperature, in particular the ambient temperature, especially only in case the vehicle is in the driving state, wherein preferably a temperature measured with a temperature sensor is compared to the at least one threshold temperature for determining the power level or power levels to be applied to the heating element and/or the time of applying the power to the heating element and/or a heating curve.

It is proposed that the power levels and/or the power jumps between 2 power levels depend on the heating device, in particular on whether a cover glass or a lens barrel is to be heated, and/or the point of time of the power jump between the 2 power levels depend on the heating device, in particular on whether a cover glass or a lens barrel is to be heated, or is fixed, with said point of time preferably being in a region from 60 sec. to 200 sec.

Still further, the method of the disclosure can comprise a third step of determining when the heating element has been active the last time, in particular after the second step, wherein preferably the determined time period since the last activation of the heating element is compared to at least one first threshold time period t(min) and in case the determined time period is shorter than the first threshold time period t(min), there is only 1 power level which is adapted to avoid icing and/or evaporate water droplets.

According to a further aspect the method can be characterized in that the first threshold time period t(min) depends on the determined temperature, wherein preferably t(min) = 12 seconds/degree (40 degree + determined temperature).

The method of the disclosure can further comprise a fourth step of applying power to the heating element with 2 power levels, in case the ambient temperature is determined to be below 0 degrees, in particular below -5 degrees, and the time period since the last activation of the heating element is determined to be at least the first threshold time period, and/or a fifth step of applying power to the heating element with 1 power level, in case the ambient temperature is determined to be below 0 degrees, in particular below -5 degrees, and the time period since the last activation of the heating element is determined to be shorter the first threshold time period, and/or the sixth step of applying power to the heating element with 1 power level, in case the ambient temperature is determined to be at least 0 degrees or at least -5 degrees.

It is also proposed that the driving state, the ambient temperature and/or the time are repeatedly determined, in particular for determining whether and when there is a point of time when to switch from the first power level to the second power level.

Thus, different heating curves were defined as a function of different ambient temperatures, in order to be able to generate the optimal amount of heat for both an ambient temperature at very low temperatures as well as at high temperatures. In fact, heating curves for temperatures below + 3° or 0° C. reflect a two-stage heating strategy. In the first stage a heat is generated which aims to melt an icing (melting enthalpy). After a defined time t-switch this heating power is reduced to prevent icing or to evaporate droplets. The time t(switch) can for example be between 60 and 200 sec depending from the heating device.

The power jump between the two heating levels applied at ambient temperatures of < +3° C. prevents damages of the heating device, in particular the heating element. Heating levels at ambient temperatures of >= +3° C. have continuous power at both stages as there is substantially no danger of damaging the heating device.

The heating curves to be applied

-   to a cover glass heater for a lens of a farsighted camera as     described e.g. in PCT/EP2019/077092 and -   to the heating device applied to the lens of a wide angle camera     differ only in the power output.

The L shaped heating element needs considerably more power for a satisfying result, due to a poorer thermal conductivity, as the heat is first directed into the entire body of the lens barrel until it heats up the camera cover surface. For cover glass heating less power is required as the energy is applied to a transparent electrically-conductive coating, preferably in form of an indium-tinoxide (ITO) layer, directly on the cover glass resulting in directly heating up the entire glass or rather lens surface.

According to a further aspect, the method may include modifying a power level provided to a heating device based on a determined vehicle speed to which the automotive camera assembly is coupled. For instance, at least one of the first power level and the second power level may be modified when the vehicle speed is determined to be below a threshold speed. In particular, the threshold speed may specifically be about 20 kilometers per hour and only the second power level may be modified. The modification may include reducing the power level. For example, the second power level may be multiplied by a reduction factor having a value between 0 and 1. Additionally, the reduction factor may be adjusted based on the speed of the vehicle.

BRIEF DESCRIPTION OF THE DRAWINGS

The foregoing summary, as well as the following detailed description, will be better understood when read in conjunction with the appended drawings. For the purpose of illustration, certain examples of the present description are shown in the drawings. It should be understood, however, that the invention is not limited to the precise arrangements and instrumentalities shown. The accompanying drawings, which are incorporated in and constitute a part of this specification, illustrate an implementation of system, apparatuses, and methods consistent with the present description and, together with the description, serve to explain advantages and principles consistent with the invention.

FIG. 1 a provides both an exploded view of a camera system of one embodiment of the present disclosure and a perspective view of the assembled camera system;

FIG. 1 b is a side view of the assembled camera assembly of FIG. 1 a , with a socket in phantom;

FIG. 1 c is a perspective view of the camera assembly of FIG. 1 b ;

FIG. 1 d is another perspective view of the camera assembly of FIG. 1 b , with the socket not shown in phantom;

FIG. 2 a is a perspective view of a heating element of an embodiment of the present disclosure to be used with the camera system shown in FIGS. 1 a to 1 d ;

FIG. 2 b is a side view of the heating element of FIG. 2 a ;

FIG. 2 c is side view of an alternative socket of the camera system of FIGS. 1 a to 1 d ;

FIG. 3 a is a perspective view of a camera system according to an alternative embodiment;

FIG. 3 b is a front view of the camera system of FIG. 3 a ;

FIG. 4 is a perspective view of a camera system of a further embodiment;

FIG. 5 is a flowchart of a heating method according to an embodiment;

FIG. 6 shows heating curves for five outside temperature ranges;

FIG. 7 is a flowchart of a heating method according to another embodiment;

FIG. 8 shows heating curves for six outside temperature ranges;

FIG. 9 shows heating curves for six outside temperature ranges; and

FIG. 10 is a schematic of a processing system associated with a heating device for an automotive camera assembly.

DETAILED DESCRIPTION

As can be seen from FIGS. 1 a to 1 d showing a camera system 1 of one embodiment of the present disclosure, a camera assembly 10 is at one end surrounded by a socket 20 and at the opposite end inserted in a housing 30. In detail, the camera assembly 10 comprises a camera 12 with a lens barrel 14 having a heat transfer ring 16 attached to its circumference. A heating element 18 is mounted on the heat transfer ring 16, and the socket 20 encompasses the lens barrel 14, the heat transfer ring 16 and a ring-shaped part 18 a of the heating element 18 to ensure a maximal contact area of said parts for optimizing a heat transfer from the heating element 18 via the heat transfer ring 16 to the lens barrel 14.

The heating element 18 comprises, in addition to the ring-shaped part 18 a, a bar-shaped part 18 b as can be best seen in FIGS. 2 a and 2 b . As the ring-shaped part 18 a is arranged substantially perpendicularly to the bar-shaped part 18 b, the heating element 18 takes a L-shape in the side view of FIG. 2 b .

The heating element 18 can be connected to a connector 19 arranged outside the socket 20, see in particular FIG. 1 d . For that purposes, the socket 20 is provided with a recess 22 allowing the bar-shaped part 18 b of the heating element 18 to enter into the socket 20, see e.g. FIG. 1 b . Via the connector 19 and a cable 42 the heating element 18 is attached to a plug 40, see FIGS. 2 a and 2 b , in order to be connectable in particular to an electronic control unit of a vehicle, not shown.

The socket 20 is also provided with an inner ring 21 projecting from its internal surface as shown in FIG. 1 a to snap-fit around the housing 30 facing edge of the unit formed by the lens barrel 14, the heat transfer ring 16 and the ring-shaped part 18 a of the heating element 18. Still further, the socket 20 is provided with openings 24 for engagement of ribs 32 provided by the housing 30, see FIGS. 1 a and 1 d .

An alternative socket 20 shown in FIG. 2 c , includes 4 recesses 22 to select one for the insertion of the bar-shaped part 18 b of the heating element 18, a rim 26 for further securing the arrangement of the heat transfer ring 16 as well as the ring-shaped part 18 a of the heating element 18 on the lens barrel 14, and a shoulder 28 provided by a S shaped cross-section at its end facing away from the housing 30 to snap fit around the unit formed by the lens barrel 14, the heat transfer ring 16 and the ring-shaped part 18 a of the heating element 18.

FIGS. 3 a and 3 b show a further camera system making usage of a tension ring 50 around the heat transfer ring 16, with the tension ring 50 being provided with a slit 52 to provide a C-shape facilitating the mounting thereof. In addition, the two end pieces 54 and 56 on both sides of the slit 52 are provided with a complimentary geometry in order to facilitate attachment to each other to secure the mounting of the tension ring 50 on the heat transfer ring 16.

The tension ring 50 can be made from metal, whereas the socket 20 preferably is provided in form of a rubber cap. Such a rubber cap can even be mounted around the metal tension ring.

The camera assembly 10 shown in FIG. 4 provides a further embodiment of this disclosure and illustrates the attachment of a temperature sensor within the socket 20 and being connected to a plug 44 via a cable 46. The temperature sensor is of particular importance with respect to realizing a heating method.

FIG. 5 depicts a heating method 100 according to an embodiment, with heating curves for outside temperatures far below 0° C. using a two-stage heating strategy. In the first stage a heat is generated which aims to melt an icing (melting enthalpy), and in a second stage, which starts after a defined time t(switch), the heating power is reduced to prevent icing or to evaporate droplets.

The method can have steps as follows:

The first step 110 is to check whether the vehicle status is correct. That is, it is checked whether the vehicle is in a driving state during which a defrost function can only be active. The vehicle status is cyclically monitored.

If the vehicle is in a valid condition, i.e. in a driving state, the second step 120 is to determine the ambient or rather outside temperature. Depending on the determined temperature, a heating curve index is set to determine the appropriate heating curve, with one or two stages.

For example there can be 5 heating curves defined by 5 heating curve indices as shown in FIG. 6 , with the following heating curve indices:

-   HC0 for temperatures above 25° C., -   HC1 for temperatures from 25° C. to 3° C., -   HC2 for temperatures below 3 ° to - 5° C., -   HC3 for temperatures below -5 ° to 15° C. and -   HC4 for temperatures below - 15° C.;

with only the heating curve index HC3 and HC4 resulting in a 2 level heating. The power levels of the heating curves defined by the heating curve indices can also differ from each other.

In an alternative aspect, there can be 5 bases defined by 5 temperature points indices as shown in FIG. 9 , with the following heating curve indices:

-   Base 0 for temperatures above 25° C., -   Base 1 for temperatures at 25° C. -   Base 2 for temperatures at 3° C., -   Base 3 for temperatures at -5° C. -   Base 4 for temperatures below - 15° C., -   Base 5 for temperatures below -25° C.;

For each temperature a linear interpolation between the bases can be done.

The power jump can take place after 60 sec.

Thus, every power level has to be applied for a specific temperature range. The first set of power levels is melting ice in case of an icing on the surface of the cover glass or lens and are called “Power Heating”. The second set of power levels are for avoiding an icing or fogging on the surface of the cover glass or lens and are called “Long Term Heating”.

The power levels also depend on whether a cover glass as described in PCT/EP2019/077092 or a lens barrel as described above is to be heated. The respective data can be provided via CAN (Controlled Area Network) from the vehicle to the heating device.

When the heating curve index has been determined, the third step 130 is to check when the vehicle has last left the status in which a heating was allowed, and the respective time span is compared with a calculated time in order to avoid that a short interruption of a journey, such as for refueling or a short shopping trip, leads to a new heating cycle with high heat input. Said calculated time t(min) depends on the outside temperature T(outside) and represents a minimum holding time: t(min) = 12 sec/°C [40° C. + T(outside)].

If t(min) is longer than the measured holding time, the heating cycle cannot be carried out with a high heat input from the start. As a result of this “Check last ECU Reset” the answer “NO” is set.

If t(min) is less than the measured holding time, the heating cycle can start from the beginning. As a result of “Check last ECU Reset” the answer “YES” is set.

In the fourth step 140 “Heater Control 1”, the time for the second stage is checked.

If the active heating time is less than t(switch), heating can be carried out with a higher power. As a result of this “Heater Control 1” the answer “YES” is set.

When t(switch) has expired in the current heating cycle, the second stage is to be used to heat with a lower power. As a result of this “Heater Control 1” the answer “NO” is set.

In the fifth step 150 “Heater Control 2”, it is checked whether the results of “Check last ECU Reset” and “Heater Control 1” both have received the answer “YES”. If this is the case, the heating cycle can be started from the beginning.

In the sixth step “Set time stamp”, t(switch) is set to 0.

Vehicle Speed Adjustment Embodiment

Another embodiment of the present disclosure is provided in FIGS. 7-9 . Along with providing many similar aspects and advantages as the systems and methods described above, this embodiment further provides a camera assembly heating process which can allow the heating power provided to a heating device for a cover glass or lens barrel of an automotive camera assembly to be modified based on the speed at which the vehicle is traveling. For instance, at lower vehicle speeds, the heating power provided to the heating device may be reduced. Among other advantages, modifying the heating power to account for vehicle speed may allow for reduced energy consumption by the heating device, while still providing adequate heating to prevent disruption (e.g. frosting, icing) of the automotive camera assembly.

FIG. 7 depicts a flowchart of a method 200 for controlling a heating device for a cover glass or lens barrel of an automotive camera assembly, in which, at 210 a camera monitor system state may be checked. Checking the camera monitor system state may involve determining whether a vehicle to which the automotive camera assembly is coupled is in a driving state and providing power to the heating device only in case the motor vehicle is in a driving state. The driving state may include when the vehicle is turned on and capable of being driven in a forward or rearward direction.

Next, at 220, the environmental temperature surrounding the automotive camera assembly may be checked. In some aspects, the environmental temperature may only be determined if the vehicle is in a driving state. The determined environmental temperature may be compared to at least one threshold temperature in order to determine the power level profile to be provided to the heating device. The threshold temperature may be between 3 and -5° C., and may specifically be 0° C.

Subsequently, at 230, the last engine control unit is checked. This may include determining the time period since the last activation of the heating device, and then comparing the determined time period since the last activation of the heating device to at least one first threshold time period. In cases where the determined time period is shorter than the first threshold time period, then the power provided to the heating device may be limited to only the second power level. This engine control unit check may prevent a short refueling stop or short shopping trip from leading to a new heating cycle with high heat input. The first threshold time period may be modified depending on the determined environmental temperature. For example, since lower environmental temperatures may cause the camera assembly to frost faster, the first threshold time period may be decreased when the environmental temperature is lower. Specifically, the first threshold time period may be calculated by adding 40° C. to the environmental temperature and then multiplying the resulting sum by a factor of 12 seconds/degree Celsius.

Table 3 details calculated threshold time periods (t_min) for temperatures ranging from -40 to -3° C., which have been calculated by adding 40° C. and then multiplying the resulting sum by 12 seconds/degree Celsius.

Temperaturen [°C] t_min [s] t_min [min] -40 0 0 -30 120 2 -20 240 4 -10 360 6 -3 444 7.4

Next, at 240, a first power level is provided to the heating device. The first power level may be provided to the heating device when the environmental temperature is compared to and determined to be below a threshold temperature. In such cases, at 250, a second power level may be provided to the heating device. Arrow 235 represents a situation in which the environmental temperature is determined to be above a threshold temperature, and the method 200 bypasses the application of the first power level and proceeds directly to the application of the second power level. The first power level may be specifically adapted to melt ice and the second power level may be a lower level, adapted to avoid icing and evaporate water droplets.

In the case where the environmental temperature is below the threshold temperature, the first power level may be provided to the heating device for a period of time before the second power level is provided. The period of time that the first power level is provided prior to the second power level being provided may be a fixed value. For example, the period of time may be between 60 seconds and 200 seconds. The period of time that the first power level is provided prior to the second power level being provided may depend on whether the automotive camera assembly comprises a cover glass or a lens barrel. For instance, a longer period of time may be used for a lens barrel camera assembly.

At least one of the first power level, the second power level, or the difference between the first and the second power levels provided may be modified depending on whether the automotive camera assembly comprises a cover glass or a lens barrel. For instance, higher first and second power levels may be provided for a lens barrel than for a cover glass camera assembly. Likewise, at least one of the first power level, the second power level, or the difference between the first and the second power levels provided may be modified depending on the determined environmental temperature. For instance, the driving state of the vehicle and the environmental temperature may be repeatedly determined in order to determine whether and when to switch from the first power level to the second power level.

Applying the first and the second power levels to the heating device may further include determining a speed of a vehicle to which the automotive camera assembly is coupled and modifying at least one of the first power level or the second power level based on the determined vehicle speed. For instance, one or more of the power levels may be modified if the vehicle speed is determined to be below a threshold speed. The threshold speed may specifically be about 20 kilometers per hour. The vehicle speed power modification may only be made to the second power level and may include reducing the second power level. In particular, modifying the power level may include multiplying the second power level by a reduction factor having a value between 0 and 1. The reduction factor may be a calculated value that is adjusted based on the speed of the vehicle. In this manner, because frosting of the camera assembly occurs more slowly at lower vehicle speeds, energy savings may be realized by reducing the applied power levels while still providing adequate heating.

The method 200 need not include each of the illustrated method steps in the particular order depicted, and may also include of the teachings described herein. For instance, the method 200 may include a first step of determining the environmental temperature surrounding an automotive camera assembly, a second step of comparing the environmental temperature to at least one threshold temperature, and a third step of providing a first power level and a second power level to a heating device coupled to the automotive camera assembly if the environmental temperature is below the threshold temperature, and otherwise providing only the second power level to the heating device, wherein the first power level is adapted to melt ice and the second power level is adapted to avoid icing and evaporate water droplets.

FIG. 8 depicts heating curves for six outside temperature ranges consistent with the methods described herein. As shown, for each temperature, a first power level (Power Boost) is provided until a period of time (t drop) is reached, at which point the first power level is reduced to a second power level (Long Term Heating). As shown, there can be six heating curves defined by six heating curve indices, where heating curve index HC3, HC4, and HC5 result in two level heating.

Table 2 details representative power levels, corresponding to FIG. 8 , for use in heating a lens barrel of an automotive camera assembly.

Heating Curve Index Temperature Range Power Boost [W] Power Long Term [W] HC 5 T= - 25° C. 11.5 5.5 HC 4 T = - 15° C. 11.5 4.0 HC 3 T = - 5° C. 10.0 3.5 HC 2 T= + 3° C. 2.5 2.0 HC 1 T = 25° C. 0.8 0.5 HC 0 T > 25° C. 0 0

Table 3 details representative power levels, corresponding to FIG. 8 , for use in heating a cover glass of an automotive camera assembly.

Heating Curve Index Temperature Range Power Boost [W] Power Long Term [W] HC 5 T= - 25° C. 2.0 1.5 HC 4 T = - 15° C. 2.0 1.0 HC 3 T= - 5° C. 1.5 1.0 HC 2 T = + 3° C. 1.0 0.7 HC 1 T = 25° C. 0.8 0.5 HC 0 T > 25° C. 0 0

For environmental temperatures between the defined temperature power bases provided in Table 2 and Table 3, linear interpolation may be utilized when determining the first power level (Power Boost) and second power level (Long Term Heating). For instance, a power level may be calculated using the below equation:

$\text{P}\text{=}\text{P}\left( \text{T}_{1} \right) + \frac{\text{P}\left( \text{T}_{2} \right) + \text{P}\left( \text{T}_{1} \right)}{\left( \text{T}_{2} \right) - \left( \text{T}_{1} \right)} \ast \text{T}_{\text{environment}}$

FIG. 9 depicts heating curves with linear interpolation between five outside temperatures, consistent with the methods described herein. For each temperature, a first power level (Power Boost) may be provided along with a second power level (Long Term Heating). As shown, there may be different boost heating powers for each temperature, with the difference in power between the two stages decreasing as the ambient temperature increases.

Additionally, the duty cycle range of the heating device may be limited during its use. For instance, the duty cycle range may be limited to be between about 3% and about 97% in order to enable a diagnosis of overload and open load detection, where duty cycle is determined using the below formula P=power R=heating device resistance and U_(T30)=Board-Voltage):

$DC = \frac{P \ast R}{U_{T30}^{2}}$

FIG. 10 is a schematic of a processing system 300 having a heating device controller 302 associated with an automotive camera assembly, consistent with the systems and methods discussed herein. The heating device controller 302 may provide power to multiple heating devices 304A, 304B, and may receive control signals and provide diagnostic feedback to a heating device processing unit 306. The heating device processing unit 306 may receive input signals from a number of other units. For instance, an environmental temperature signal 308 may be provided to the heating device processing unit 306 from a CAN input unit 310. Similarly, an ECU system state signal 312 may be provided to the heating device processing unit 306 from an MCU input unit 314. The heating device processing unit 306 may include a diagnostic interface 316 that may receive input signals and provide feedback to a diagnostic communication manager (DCM) 318 and a diagnostics event manager (DEM) 320. Furthermore, the DCM 316 may communicate to an NVM parameter unit 322, which is also in communication with the heating device processing unit 306.

It will be appreciated by those skilled in the art that changes could be made to the embodiments described above without departing from the broad inventive concept thereof. It is understood, therefore, that the invention disclosed herein is not limited to the particular embodiments disclosed, and is intended to cover modifications within the spirit and scope thereof.

Reference Signs 1 camera system 10 camera assembly 12 camera 14 lens barrel 16 heat transfer ring 18 heating element 18 a ring-shaped part 18 b bar-shaped part 19 connector 20 socket 21 inner ring 22 recess 24 opening 26 rim 28 shoulder 30 housing 32 rib 40 plug 42 cable 44 plug 46 cable 50 tension ring 52 slit 54 end piece 56 end piece 100 first heating method 110 - 160 method steps 200 second heating method 200 - 250 method steps 300 processing system 302 heating device controller 304A first heating device 304B second heating device 306 heating device processing unit 308 environmental temperature signal 310 CAN input unit 312 ECU system state signal 314 MCU input signal 316 diagnostic interface 318 diagnostic Communication Manager (DCM) 320 diagnostics event manager (DEM) 322 NVM parameter unit 

What is claimed is:
 1. A method for controlling a heating device for a cover glass or lens barrel of an automotive camera assembly, the method comprising: determining the environmental temperature surrounding an automotive camera assembly; determining a first power level and a second power level based on the environmental temperature; and providing at least one of the first power level and the second power level to a heating device coupled to the automotive camera assembly, wherein the first power level is adapted to melt ice and the second power level is adapted to avoid icing and evaporate water droplets.
 2. The method according to claim 1, further comprising: comparing the environmental temperature to at least one threshold temperature; and providing the first power level and the second power level to the heating device if the environmental temperature is below the threshold temperature, and otherwise providing only the second power level to the heating device.
 3. The method according to claim 2, further comprising: determining whether a vehicle to which the automotive camera assembly is coupled is in a driving state and providing power to the heating device only in case the motor vehicle is in a driving state.
 4. The method according to claim 3, wherein the step of determining the environmental temperature only occurs if the vehicle is determined to be in the driving state.
 5. The method according to claim 2, wherein the first power level is provided to the heating device for a period of time before the second power level is provided when the environmental temperature is below the threshold temperature.
 6. The method according to claim 5, wherein at least one of the first power level, the second power level, and the difference between the first and the second power levels provided is modified depending on whether the automotive camera assembly comprises a cover glass or a lens barrel.
 7. The method according to claim 5, wherein at least one of the first power level, the second power level, and the difference between the first and the second power levels provided is modified depending on the environmental temperature.
 8. The method according to claim 5, wherein the period of time that the first power level is provided prior to the second power level being provided is a fixed value between 60 seconds and 200 seconds.
 9. The method according to claim 5, wherein the driving mode of the vehicle and the environmental temperature are repeatedly determined in order to determine whether and when to switch from the first power level to the second power level.
 10. The method according to claim 5, wherein the period of time that the first power level is provided prior to the second power level being provided depends on whether the automotive camera assembly comprises a cover glass or a lens barrel.
 11. The method according to claim 2, wherein the threshold temperature is between 3 and -5° C.
 12. The method according to claim 2, wherein the threshold temperature is 0° C.
 13. The method according to claim 1, further comprising: determining the time period since the last activation of the heating device; and comparing the determined time period since the last activation of the heating device to at least one first threshold time period, wherein only the second power level is provided to the heating device if the determined time period is shorter than the first threshold time period.
 14. The method according to claim 11, wherein the first threshold time period is modified depending on the determined environmental temperature.
 15. The method according to claim 12, wherein the first threshold time period is calculated by adding 40° C. to the environmental temperature and then multiplying the resulting sum by a factor of 12 seconds/degree Celsius.
 16. The method according to claim 1 further comprising: determining a speed of a vehicle to which the automotive camera assembly is coupled; and modifying at least one of the first power level and the second power level when the vehicle speed is determined to be below a threshold speed.
 17. The method according to claim 15, wherein the threshold speed is about 20 kilometers per hour.
 18. The method according to claim 15, wherein only the second power level is modified.
 19. The method according to claim 15, wherein modifying the power level includes reducing the power level.
 20. The method according to claim 18, wherein reducing the power level includes multiplying the second power level by a reduction factor having a value between 0 and
 1. 21. The method according to claim 19, wherein the reduction factor is adjusted based on the speed of the vehicle. 